Heat treatment of metal bodies.



J.H.BARKBR. HEAT TREATMENT OF METAL BODIES.

APPLICATION FILED JUNE 4, 1913.

1,085,523. Patented Jan. 27, 1914.

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JOHN HENRY BARKER, 0F BIRMINGHAM, ENGLAND, ASSIGNOR TO BIRMINGHAM METAL & MUNITIONS COMPANY LIMITED, OF BIRMINGHAM, ENGLAND.

HEAT TREATMENT OF METAL BODIES.

bodies, and, more especially, the annealing of metal cartridge cases at the ends in which the bullets are secured.

In the manufacture of metallic, cartridges for small arms the outer end or short portion 'of the case embracing the bullet must be necked or reduced in diameter. Such necking involves the performance of work on the metal setting up internal stresses. Where the cases are to be loaded with an explosive in the form of grains or flakes the stresses are removed by an annealing process prior to loading. \Vith cordite or other-explosive in the form of tubes, strands or strips it is necessary to insert the charge prior to necking. Hitherto it has not been found practicable to anneal the necks of the cases after loading. The presence of these stresses in the metal is liable when the cases are fired to develop splits or cracks, and if the cartridges. are stored for several years, more especially in tropical climes, similar cracks develop spontaneously causing the bullets to become loose or to fall out.

With this invention the annealing is effected by heating electrically only the necked or unloaded portions of the cases, and at such a rate that the operation occupies insufiicient time for the other portions of the cases to attain a temperature liable to ignite the charge, or at such a rate that such por tions can readily be maintained at a safe temperature by an air current or other equivalent means.

The invention comprises means as hereinafter described for automatically passing an electric current through the cartridge necks.

Referring to the accompanying sheet of explanatory drawings, the diagram illustrates by vertical section one convenient form of apparatus for carrying the invention into effect for the annealing of car- Specification of Letters Patent.

Application filed June 4, 1913.

Patented Jan. 27, 1914.

Serial No. 771,624.

and 0, one of which (1)) comp-rises an annular element which is insulated from the other (0) and is adapted to bear on the cartridge case cl below the neck. The electrode 0 is a plain or plug like element mounted coaxially with the annular electrode 5 and adapted to bear on the outer end of the neck of the case as shown in the diagram. The annular electrode is carried by spring controlled rods 0 from a plate f which is attached to the lower end of a plunger 9 arranged to slide within the plunger a and maintained in its lowermost position by aspring h. Suitable electrical insulation 11 is provided between the parts a and g, and also between the parts f and g. The annular electrode 6 is connected to the source of electricity through the flexible conductor 7', the supporting flange or plate f and a con ductor K while the plug or plain electrode c is connected to the source of electricity by flexible conductors Z attached to a collar 9 fore the electrodes are removed from the cartridge.

The switch is illustrated diagrammatically in the drawings by an arm 1' secured to a and fitted with a brush or other contact 8 which is adapted to join the fixed contacts t. The movement of a against the spring h after the electrodes have been brought into contact with the case 03 is utilized to close the switch. The corresponding reverse movement opens the switch before the electrodes are separated from the case (i.

Completion and interruption of the supply of energy may be performed at any suitable position in the circuit. In the case of an alternating current, the switch is preferably placed in the primary coil of a transformer, and in the case of direct current the switch may be placed in circuit With the magnet coilsof a dynamo by which the required current is generated, In both arrangements the object is to place the switch in the partmf the system where the current is least.

The cartridges are preferably moved into and out of the operative position by any or dinary intermittently revolving horizontal table indicated diagrammatically by m, and formed with suitable apertures or pockets "/1. Operation of the tableis effected by any ordinary means.

Vl hen a case (Z is brought by the table at into position beneath the reciprocating head a the latter descends until the annular and plug electrodes Z) and 0 make contact with the case at the parts above mentioned. '1 he manner of supporting the electrode 7) through rods 6 from the flange 7 insures proper contact of both electrodes with the cartridge case notwithstanding any slight variations in the length ofjhe case. Fur-- their movement (if-the reciprocating head 0 completes the electric circuit through the switch aforesaid, and iii-consequence current flows to the portion of the case between the electrodes. During such extra movement or tridgc is removed.

the head or plunger a the plunger 9 remains stationary. By employing a large currentthe neclr. of the case can be raised practically instantly to the required temperature. The magnitude of the current varies for different classes of Work, but the necessary amount for any particular kind of work can readily be determined.

It is advantageous not to effect aperfect electrical contact at the outer end of the case, as an imperfect contact tends to pro duce greater heating at that part than when the contact is complete, and in consequence the greatest heat is produced at the part of ,the case remotest from the explosive. Ordinarily the ends of the cases are slightly rough and such roughness is sufiicient to produce a slightly imperfect contact with the plunger which results in the aforesaid greater heating at the extremity of the case. After heating the current is interrupted, the electrodes are withdrawn and the car- The operation is then repeated on the next. case.

By proceeding above described the ucclrs of the cartridges can so rapidly be heated and the amount of heat produced is I so quickly dissipated by the surrounding air after the circuit has been broken that no time is allowed i'or undue heating of the body of the cartridge and its contained 'horgc. In consequence the annealing operion is quite safely as well as effectively ii desired an air blast from a jet 0 may directed on to the body of the case dun n heating 1 to expedite subsequent coolbut ll. is not essential. Also, it dosircd, a cover plate may be placed over the neck prior to heating to protect the body part from heat, or the electrode 7) may be water cooled for preventing excessive heatint; ot the main portion of the case. A pen messes forated guard 7) may be arranged around the electrode 0 ii. desired.

The invention while especially suitable for annealing cartridge cases when loaded as above described is not limited to such use, asit may be employed for annealing; before loading Also it-may be utilized for such purposes as the local annealing or heating of other like tubular articles. Further, the in' vention is not limited to the mechanical details herein described as these may be varied to meet different services and requirements.

Having thus described my invention What I claim as new and desire to secure by Letters Patent is:

1. In means for the electrical annealing or like heat treatment of metal cartridge cases and lilie tubular articles, the combination comprising an annular and a plain electrode adapted to make contact with the article at the ends of the part to be treated, and means producing conjoint and relative movements of the electrodes, substantially as described.

2. In means for the electrical annealing or like heat treatment of metal cartridge cases and like tubular articles, the combination cases and like tubular articles, the combina- 4 tion comprising a plunger, a plain electrode rigidly secured to said plunger, a flange se cured to but insulated from said plungc'r, rods depending from the flange and movable therethrough, an annular electrode carried by said rods, and springs in confunction with the rods, substantially as descri ed.

5. In means for the electrical annealing or like heat treatment of metal cartridge cases and like tubular articles, the combination comprising a pair of inner and outer telescopic plungers, an annular and a plain electrode relatively movable in an axial direction and carried by the inner plunger, and means actuated with the movements of theouter plunger whereby an electric circuit is closed and opened, substantially as described.

6. In means for the elcctrica annealing or like i102 treatment of metal cartridge cases and like tubular articles, the combination comprising a pair of inner and outer telescoplc and relatively insulated plungers, a spring inserted between the plungers, a plain electrode rigidly secured to the inner plunger, a flange secured to but insulated from the inner plunger, rods depending from and movable through the flange, an annular electrode carried by the said rods, and springs inserted between the rods and the flange, substantially as described.

7. In means for the electrical annealing or like heat treatment of metal cartridge cases and like tubular articles, the. combination comprising apair of inner and outer telescopic and relatively insulated plungers, a spring inserted between the plungers, a plain leetrode rigidly secured to the inner plun; ger a flange secured to but insulated from the inner plunger, rods depending from and movable through the flange, an annular electrode carried the said rods, springs inserted between the rods and the flange, and a switch actuated by the outer plunger, substant-ially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

JOHN HENRY BARKER.

i' i itnesses ERNEST PARKER, Jenn MORGAN. 

